dset ^sample.grib
index ^sample.idx
title sample grib file
dtype grib 
options yrev
undef 9.999E+20
XDEF 360 linear 0.0 1.0
YDEF 181 linear -90.0 1
ZDEF 4 levels 1000 850 500 200
TDEF 3 linear 00Z02apr2004 6hr
VARS 2
u 4 33,100 u wind [m/s]
v 4 34,100 v wind [m/s]
ENDVARS